Reverse-current cut-out.



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Leonard Andrews by M UNITED STATES rLEONARD ANDREWS, OF MANCHESTER, ENGLAND, ASSIGNOR TO PATENT, orriori.

STANLEY G. I. ELECTRIC MANUFACTURING COMPANY, A COR- PORATION OE NEW JERSEY.

REVERSE-CURRENT GUT-OUT.

Specification of Letters Patent.

Patented Aug. 28, 1906.

Application filed Juueig.- i905, Serial' No. 265,899.

To @ZZ whom it may concern.-

Beit known that I, LEONARD ANDREWS', a subject ofthe King of Great Britain, residing at Manchester, England, have invented certain new and useful Improvements in Reverse-CurrentA Cut-Outs, of which the following is aspecification.

My invention relates to protective devices for electric circuits; and it' consists in an improvement in the Ireverse-current cut-out disclosed in United States Letters Patent No. 751,442, issued to me February 9, 1904. In

that patent I disclosed a cut-out comprising' a magnetic core having two coils Wound on different portions of its length and connected one in series with and the other in shunt to the electric current to be protected, and a movable membery shunting each of the portions of the magnetic core on which the coils are wound and adapted by its movement to open a switch in the circuit to be protected.

. In some cases it is desirable that a cut-out of or to operateonly on' a reverse current. Ii.

accomplish this result by providing means for varying the relative reluctances or eective cross-sections of the two portions of the magnetic core on which the shunt and series windings are placed. If the cross-sectionoi1 the ortion of the core on which the shuntwinding is placed, is made greater than the cross-section of that part ofthe core carrying the series winding, a heavy overload-current will saturate the portion ofthe core carrying the current-coil, but cannot saturate that vportion of the core carrying theshunt-coil.

The portion of the core carrying^the shuntcoil consequently remains at all times an effe'ctive magnetic shortcircu'it for the movable member, and the device will not operate' on'an overload-current of any amount. On the other hand, if the cross-section of the portion ofthe core carrying the current-coil is increased relatively to that portion carrying the potential coil, the latter portion may become saturated by a heavyoverload-current, and consequently the movable member forming a magnetic shunt thereto Will be actuated.

By adjusting the relative cross-section of the v two portions of the core carrying the two coils, 'the device may be adjusted to act on any desired overload.

My yinvention will best be understood by reference to the accompanying drawings, in

' Figure 1 shows anvelevation, partly in cross-section, of an improved reverse-current cut-out arranged 1n accordance with my 1nvention; and Fig. 2 is a diagram of connecv,

tions.

Referring iirst to Fig. 2, A represents a direct-current generator connected to the busbars B.l It is assumed that. it is desired to prevent a iiow off'current fromthe bus-bars to the generator in case the voltage ofthe generator fails for any reason, such as a shortcircuit, a breaking of the field, failure of the l prime mover, or other cause.

- Although I. have illustrated my device as applied to the protection of a generator, it will be understood that it is not limited to this particular application, butmay be used v to protect any electric circuit against a rei versal of current flow therein.

, In Fig. 2, C represents a switch or circuit-fbreaker inserted 1n the circuit of generator A -and provided with a latch c, adapted to hold the switch in closed position. D represents the protective device, which comprises two coils E and E', the first of which is connected in shunt to the generator A and the second in series therewith. trolled by the coilsE and E in the manner which will be hereinafter explained and adapted to engage the vlatch c, so as to trip e represents a plunger conthe switch C and to open the circuit of generator A.

The construction of the device D is shown in 1., In this'igure the ceils E and E areA shown mounted, res ectively, on two hollowrl cores E and F', whic are connected by yokes G Gr-oi magnetic material. These yokes, together with the hollow cores, form a closed magnetic circuit. The plungere is adjusthollow cores on which the shunt and series coils are wound. When the plunger c is drawn up, it strikes a hammer-blow upon the in i, upon which the latch c rests, so that the atch is mo\ved on its pivot to release the Switch andropen the circuit in the manner that has heretofore been explained. The coils E and E are so connected that while the current in the main circuit is in its normal direction their magnetomotive forces are in the same direction in the closed magnetic circuit formed by the hollow cores F and F and the yokes G G. Consequently there is little or no tendency for any flux to pass through the open magnetic shunt formed by the plunger e. If, however, the current in the main circuit is reversed, the direction of the magnetornotive force of the series coil E will be reversed in direction, so that the coils E and E will oppose their magnetomotive forces in the closed magnetic circuit, tending to divert the flux of both coils through the shunt formed by the plunger e.' The plunger will consequently be drawn up, tripping the switch, as has been heretofore explained.

New if the action of the de'vice upon an over-v load-current in the normal direction is considered itis obvious that its operation will depend upon what portion of the closed magnetic circuit irst becomes saturated. Thus if the core von which the coil E is mounted becomes saturated iirst the remaining portion of the magnetic circuit will remain unsaturated and continue to act as a magnetic short circuit for the movable plunger e. Consegluently under these conditions -the device wi not o erate on any overload-current in the norma direction however-heavy. If, on the other hand, the portion ofthe closed magnetic circuit on which 'the potential coil E is w'ound becomes saturated first, the increasing iux due to the current-coil will be diverted through the movable lungere, and when the diverted or leakage ux reaches a predetermined amount, the plunger will be drawn up, so as to trip the switch. Under these conditions the device will o erate not only as a reverse-current cut-out, ut also as anoverload cut-out.

Sometimes one mode of operation and sometimes the other is desirable, and in orderv that the device may be conveniently adjusted for either operation, I provide a core J ,which may be adjustably inserted within either of the hollow cores F or F. For the purpose of adjustment the cores F and F are provided with internally-screw-threaded caps K and` K', res ectively, and the core J is externally screw-t eaded, as shown. By this means the position of the core J within either of the hollow cores may be conveniently and accurately adjusted. The core J carries -alockla reverse-current protctive'device comprisceases nut y', by means of which it may be locked firmly in position after it has been properly set.

Many modications may be made in the structure and arrangement of parts, and accordingly I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the appended claims to'A cover all modifications which are within the scope ol my invention.

W'ihat I claim as new, and desire to secure by Letters Patent of the United States, is-

l. In combination with an electric circuit, a reverse-current protective device comprising a magnetic core, two windings carried on two different portions of said core and connected in shunt and in series respectively with said circuit, a movable member forming a magnetic shunt for each of said two portions of said core, means actuated by the movement of said member for opening said electric circuit, and means for adjusting the relative reluctanccs of said two portions.

2. In combination with an electric circuit, a reverse-current protective device comprising a magnetic core, two windings carried on two different portions of said core and connected in shunt and in series respectively with said circuit, a movable member forming a l magnetic shunt for each of said two portions of said core, means actuated by the movement of said member for opening said electric circuit, and means for adjusting the relative effect cross-sections of said two portions.

3. In combination with an electric circuit, a reverse-current protective device comprising' a closed magnetic circuit, two windings carried on two portions of said magnetic circuit, and connected in shunt and in series respectively with said electric circuit, a mova le plunger forming a normally open magnetic shunt for each of said two portions,l means actuated by the movement of said plunger for opening said electric circuit, and means for adjusting the relative reluctances of said portions.

4. In combination with an electric circuit,

ing a magnetic circuit includingtwo ho low cores, two windings carried respectively on said cores and connected respectively in shunt and in series with said electric circuit, a movable member forming a magnetic shunt to each of said cores, means actuated by the movement of said member for 'opening said electric circuit, and a core adapted to be adjustably inserted in either of said hollow cores.

5. In combination with an electric circuit, a reverse-current protective device com rising a magnetic circuit including two no low cores each provided with'an rinternal screwthreadhtwo windings carried respectively on said cores and connected respectively in shunt and in series with saidfelectric circuit, a

IZO

movable member iormi'ng a magnetic shunt for each of said cores, means actuated by the movement of said membrior o 'ening said electric circuit, and an externa@ ly screwthreaded core adapted to ser ed in either of said holbw cores.

6. In combination with an electric circuit, a reverse-current protective device com rising a magnetic circuit including two hollow cores, two windings -carried respectively on said cores and connected respectively shunt and-in series with said electric circuit, a movable member forming a magnetic shunt to each of said cores, means actuated by the movement of said member for opening said electric circuit, a core adapted to be adjustably inserted in' either vof said hollow cores, and means for locking said core in position. 7. In combination with an electric circuit, a reverse-current protective device com rising a magnetic circuit including two ho low cores each provided with an internal screwthread, two windings carried respectively on said cores 'and ,connected respectively lin shunt and in series with said electric circuit, a

be adjustably in-v Inova blemember forming a magnetic shunt for each of said cores, means actuated by the movement/ of said member for opening said electric circuit, an externally-screw-threaded Y lng a magnetic core, two windings carried on two different portions of said core and con',- nected in shunt and in series respectively with said circuit, a movable plunger forming a magnetic shunt for each of said portions and'adapted when moved to engage said latch, and means for adjusting the relative reluctances of said two portions.

In witness whereof I have hereuntoset my hand this 16th day of June, 1905'.

LEONARD *ANDREWS Witnesses EDGAR CAFFALL, L.' C. Foss. 

